The invention relates to a method and a corresponding system for establishing a communication between a charging station and a vehicle.
Vehicles with an electric drive typically have a battery, in which electrical energy for operating an electric motor of the vehicle can be stored. The battery of the vehicle can be charged with electrical energy from a power supply system. For this purpose, the battery is coupled to the power supply system in order to transfer the electrical energy from the power supply system into the battery of the vehicle. The coupling may take place in a wire-bound manner (for example by way of a charging cable) and/or a wireless manner (for example on the basis of an inductive coupling between a charging station and the vehicle).
One way that is used for the automatic, cableless, inductive charging of the battery of the vehicle is that the electrical energy is transferred to the battery by way of magnetic induction from the ground to the underfloor of the vehicle over the underfloor clearance 120. This is shown by way of example in FIG. 1. In particular, FIG. 1 shows a vehicle 100 with an energy store 103 for electrical energy (for example with a rechargeable battery 103). The vehicle 100 includes a so-called secondary coil in the vehicle underfloor, the secondary coil being connected to the energy store 103 by way of an impedance matching circuit (not shown) and a rectifier 101. The secondary coil is typically part of a so-called “Wireless Power Transfer” (WPT) vehicle unit 102.
The secondary coil of the WPT vehicle unit 102 may be positioned over a primary coil, the primary coil being fitted for example on the floor of a garage. The primary coil is typically part of a so-called WPT base unit 111. The primary coil is connected to a power supply 110 (in this document also referred to as the charging unit 110). The power supply 110 may have a radio-frequency generator, which generates an AC current (alternating current) in the primary coil of the WPT base unit 111, whereby a magnetic field is induced. This magnetic field is also referred to in this document as the electromagnetic charging field. The electromagnetic charging field may have a predefined charging field frequency range. The charging field frequency range may lie in the LF (low-frequency) range, for example at 80-90 kHz (in particular at 85 kHz).
With sufficient magnetic coupling between the primary coil of the WPT base unit 111 and the secondary coil of the WPT vehicle unit 102 over the underfloor clearance 120, a corresponding voltage, and consequently also a current, is induced in the secondary coil by the magnetic field. The induced current in the secondary coil of the WPT vehicle unit 102 is rectified by the rectifier 101 and stored in the energy store 103 (for example in the battery). Thus, electrical energy can be transferred in a wireless manner from the power supply 110 to the energy store 103 of the vehicle 100. The charging operation may be controlled in the vehicle 100 by a charging controller 105 (also referred to as the WPT controller 105). For this purpose, the charging controller 105 may be designed to communicate, for example wirelessly, with the charging unit 110 (for example with a wall box) or with the WPT base unit 111.
For an effective energy transfer by way of the electromagnetic charging field, it is typically required that the WPT vehicle unit 102 is positioned relatively accurately over the WPT base unit 111. This positioning may be assisted by determining the position of the vehicle 100 in relation to the WPT base unit 111. Furthermore, it is desirable for an efficient charging operation that a communication connection between the charging controller 105 of the vehicle 100 and the charging unit 110 is established, for example to start the charging communication for the charging operation, in a way that is efficient (i.e. as far as possible without intervention by a driver of the vehicle 100) and quick.
The present document is concerned with the technical object of establishing such a communication connection efficiently and quickly, in particular when there are a large number of possible WPT base units 111 or a large number of charging units 110.
This and other objects are achieved according to one aspect of the invention by a method for establishing a wireless communication connection between a vehicle communication unit of a vehicle and a charging station communication unit of a charging station. The charging station may be in particular a charging station for wireless (in particular inductive) and/or contactless (for example on the basis of a charging cable actuated by a robot arm) charging of an electrical energy store of the vehicle. The charging station may comprise a WPT base unit for the inductive energy transfer. The communication units may be designed to establish a wireless LAN (Local Area Network) connection (for example in accordance with IEEE 802.11). In particular, the charging station communication unit may comprise for this purpose a wireless LAN access point.
The method comprises the emitting of a low-frequency (LF) request signal by way of an LF transmitting unit of the vehicle. In this case, the LF request signal indicates an identifier with respect to the vehicle or an identifier with reference to the vehicle. In particular, the LF request signal may comprise items of information with respect to the identity of the vehicle by which the LF request signal is emitted. The LF request signal may comprise a request signal of a keyless access function and/or of a keyless engine starting function of the vehicle. A transmitting frequency of the LF transmitting unit and of the LF request signal may lie in an LF frequency range of 20-140 kHz.
The method further comprises the receiving of the LF request signal by an LF receiving unit of the charging station. The LF receiving unit of the charging station may be constructed like the receiving unit of a vehicle key with a keyless access function and/or keyless engine starting function. Typically, the LF request signal has only a very limited range (for example of 5, 4, 3 meters or less). It can consequently be inferred from the reception of the LF request signal by the LF receiving unit of the charging station that the vehicle is in a limited vicinity (which corresponds to the range of the LF request signal) of the charging station.
The method also comprises the emitting of items of information with respect to the identifier in a broadcast message by the charging station communication unit. The broadcast message may be emitted periodically (for example 10 times per second) by the charging station communication unit, in order to indicate that the charging station communication unit is within a range that makes it possible to establish a communication connection. Apart from the information with respect to the identifier of the vehicle, the broadcast message may also comprise items of information relating to the identification of the emitting charging station communication unit (for example a WLAN SSID). The broadcast message may in particular comprise a wireless LAN beacon message or a beacon message. The items of information with respect to the identifier of the vehicle may be arranged in a vendor extension of the beacon message.
The method also comprises the receiving of the broadcast message by the vehicle communication unit. The vehicle communication unit or the vehicle may then check whether the broadcast message comprises the items of information with respect to the identifier. A wireless communication connection between the vehicle communication unit and the charging station communication unit can be established if (possibly only if) it is determined that the broadcast message comprises the items of information with respect to the identifier. In particular, a request for establishing a wireless communication connection between the vehicle communication unit and the charging station communication unit may be emitted by the vehicle communication unit.
The insertion of items of information with respect to the identifier into the broadcast message makes it possible for the vehicle to determine in a cost- and time-efficient way which charging stations are in the direct vicinity of the vehicle. Furthermore, it is made possible in this way for a communication connection between the charging station and the vehicle (for example for carrying out the charging communication for a charging operation) to be established quickly.
The method may further include receiving by the vehicle communication unit a large number of broadcast messages from a corresponding large number of charging station communication units of a corresponding large number of charging stations. For example, in a parking lot or in a parking garage, charging stations may be located in adjacent parking spaces. In this case, the LF request signal may possibly be received by a number of charging station communication units of a number of charging stations. Furthermore, the vehicle communication unit may in this case receive a large number of broadcast messages from different charging station communication units, it being possible for one or more of the broadcast messages to contain the items of information with respect to the identifier of the vehicle.
The method may further include determining one or more of the large number of broadcast messages that comprise(s) the items of information with respect to the identifier. Furthermore, correspondingly one or more charging station communication units that have emitted the one or more determined broadcast messages may be determined from the large number of charging station communication units. Consequently, the one or more charging stations that are located at a distance from the vehicle that is less than or equal to the range of the LF request signal can be determined.
The method may also include selecting one of the determined one or more charging station communication units for establishing the wireless communication connection. The selection may for example be performed manually by an occupant of the vehicle. For this purpose, items of information with respect to the one or more charging stations that correspond to the one or more determined charging station communication units may be emitted, so that the occupant of the vehicle can select a suitable charging station. An optical output may possibly be generated, identifying the charging station of the selected charging station communication unit in order to facilitate positioning at the selected charging station.
The broadcast message of a charging station communication unit may further comprise items of information with respect to a signal strength with which the LF request signal was received by the charging station communication unit. On the basis of the signal strength it is possible to determine for example the relative position and/or the distance between the vehicle and the charging station. The selection of the charging station communication unit for establishing the wireless communication connection may take place in dependence on the signal strength of the LF request signal. In particular, a charging station that can be approached by the vehicle in an advantageous way may be selected.
The method may further including determining items of information with respect to a trajectory of the vehicle. In particular, a driving direction and/or a steering angle of the vehicle may be determined. The charging station communication units may then be selected for establishing the wireless communication connection (possibly also) in dependence on the items of information with respect to the trajectory of the vehicle. This allows the selection of an “approachable” charging station to be improved further.
According to a further aspect, a charging station for charging an electrical energy store of a vehicle is described. The charging station comprises an LF receiving unit, which is designed to receive a low-frequency. (LF) request signal from an LF transmitting unit of a vehicle in a vicinity of the charging station. In this case, the vicinity of the charging station is typically limited by a range of the LF request signal. The LF request signal comprises an identifier (or an ID) with respect to the vehicle.
The charging station further comprises a charging station communication unit, which is designed to emit items of information with respect to the identifier in a broadcast message. The charging station communication unit is further designed to establish a wireless communication connection between the vehicle communication unit and the charging station communication unit in response to a request from a vehicle communication unit of the vehicle.
According to a further aspect, a vehicle (in particular a road vehicle, for example a passenger car, a truck or a motorcycle) is described. The vehicle has a low-frequency, LF for short, transmitting unit, which is designed to emit an LF request signal, the LF request signal indicating an identifier with respect to the vehicle. Furthermore, the vehicle has a vehicle communication unit, which is designed to receive a broadcast message from a charging station communication unit of a charging station. The vehicle communication unit is further designed to check whether the broadcast message includes items of information with respect to the identifier. Furthermore, the vehicle communication unit is designed to initiate the establishing of a wireless communication connection between the vehicle communication unit and the charging station communication unit if the broadcast message includes items of information with respect to the identifier.
According to a further aspect, a software (SW) program is described. The SW program may be designed to be run on one or more processors (for example partly on a processor of the charging station and partly on a processor of the vehicle), in order thereby to perform the method described in this document.
According to a further aspect, a storage medium is described. The storage medium may include an SW program, which is designed to be run on a processor, in order thereby to perform the method described in this document.
It should be noted that the methods, devices and systems described in this document can be used both alone and in combination with other methods, devices and systems described in this document. Furthermore, any aspects of the methods, devices and systems described in this document may be combined with one another in various ways.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.